We've been long aware about the possible harm that high-fat-diet could do for our cardiovascular system. Taking greasy fries out of our meals is a way to help us stay away from heart disease, high blood pressure and diabetes, but it may sound unusual to associate it to doing any good to our immune system. Recent studies suggested that high fat diet could cause more severe diseases in autoimmune diseases. The study published in Immunity ( Haghikia and Jo¨rg et al. ) studied the role of two types of fatty acids, short-chain and long-chain fatty acid, on autoimmune diseases. Short chain fatty acids (SCFAs) role are solely metabolized by gut bacteria from otherwise indigestible carbohydrates (e.g. dietary fiber); on the other hand, long-chain FAs (LCFAs) come from regular dietary fat. They kept mice that had neural autoimmune disease (autoimmune encephalomyelitis/EAE) with food enriched with SCFAs, LCFAs or control food to compare disease progression. As a result, mice treated with L...